In the lumber industry, it is generally known that sorting wooden logs upstream to the debarking line presents economical and operational advantages as compared to downstream sorting operations performed on the resulting wood products. Sorting by wood species can be carried out either as part of timber harvesting or in the lumberyard of the mill, and is generally performed by human operators through visual inspection of bark and/or cut-off surfaces of each piece of timber. However, manual inspection is time-consuming and generally exhibits a high misidentification rate. Although a high reliability of wood species identification may be obtained with microscopic inspection of wood fiber samples, such a laboratory technique cannot be practiced in a mill environment. In the past, some automated techniques aimed at wood species identification have been proposed. In U.S. Pat. No. 6,072,890, an indicator liquid is sprayed onto a fresh cut end of each piece of lumber to produce a characteristic reaction, e.g. based upon pH, and after a suitable interval of time, the coated ends of the lumber pieces are optically scanned for spectrographic analysis to identify the species of the piece of lumber, e.g. as between spruce and fir. Another technique disclosed in U.S. Pat. No. 5,071,771 is based on production of an ion mobility signature representing a wood sample, followed by comparing signatures to identify the species of the wood sample. However, such sample-based techniques do not provide wood species identification in real-time. In U.S. Published Patent application no. 2012/0105626, wood species identification is performed through fluorescence-based detection of pitch (resin) characteristics of wood surface exposed to a beam of UV radiation, causing pitch on or within the workpiece to emit visible light. Moreover, U.S. Pat. No. 5,406,378 discloses to perform wood species identification through irradiation of a wood sample with infra-red radiation intense enough to introduce microstructural modifications of the material surface, which can be detected measuring the intensity of the optical light reflected. However, such known optical techniques are not adapted to species identification for raw wooden logs, due to the presence of bark covering the wood fibers.